In the UK we don't generally get insurance coverage from credit cards so we always buy the full cover - it's expensive but worth it for peace of mind. I've heard from fellow timeshare owners from the US that their credit cards give some cover, but not full. I know someone who didn't have the right coverage and had to pay $1200 up front for some minor bumper damage because the other party wouldn't admit liability.
It is a developed and relatively safe destination by regional standards, but it's still something of a law unto itself in many aspects!